Lighting circuit

Abstract

The present invention provides a lighting circuit capable of suppressing the effects of power supply voltage fluctuations. The lighting circuit is applied to a vehicle turn signal indicator and includes: a first drive circuit that supplies a first drive current to a first light source including at least one light-emitting element; a first resistor and a first switch that are disposed in series between a power supply line to which a power supply voltage is applied and a ground line; and a first control circuit that turns on the first switch when the power supply voltage is lower than a first predetermined value and turns off the first switch when the power supply voltage is higher than the first predetermined value.

Description

Technical Field

[0001] The invention relates to a lighting circuit. Background Art

[0002] As a vehicle lighting fixture, for example, a vehicle turn signal lamp (hereinafter referred to as a "turn signal lamp") is known that uses a so-called sequential method to sequentially illuminate multiple light sources (e.g., Patent Document 1). Power is supplied from the vehicle's battery to a lighting circuit used in the vehicle turn signal lamp.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Laid-Open No. 2017-119449 Summary of the Invention

[0006] Problems to be solved by the invention

[0007] The vehicle's battery voltage (hereinafter referred to as the power supply voltage) is not always constant but decreases with use. When the power supply voltage is high, ICs and other components in the lighting circuit consume more power (and generate more heat), potentially causing malfunctions. When the power supply voltage is low, power consumption is low, potentially leading to false detection of a disconnection.

[0008] The present invention has been made in view of the above-mentioned conventional problems, and an object of the present invention is to provide a lighting circuit capable of appropriately controlling power consumption in response to changes in power supply voltage.

[0009] Means used to solve problems

[0010] The present invention mainly solves the above-mentioned problems and is a lighting circuit applied to a direction indicator light for a vehicle, wherein the lighting circuit comprises: a first drive circuit, which supplies a first drive current to a first light source including at least one light-emitting element; a first resistor and a first switch, which are arranged between a power line to which an external power supply voltage is applied and a ground line, and are connected in series; and a first control circuit, which turns on the first switch when the power supply voltage is lower than a first predetermined value, and turns off the first switch when the power supply voltage is higher than the first predetermined value.

[0011] Effects of the Invention

[0012] According to the present invention, it is possible to provide a lighting circuit capable of appropriately controlling power consumption in response to changes in power supply voltage. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 11 is a diagram showing an example of the lighting unit 10 mounted on the vehicle 1 .

[0014] Figure 2 10A is a schematic block diagram showing an example of the system configuration of the turn signal lamp 10A.

[0015] Figure 3 This is a schematic block diagram showing an example of the configuration of the lighting circuit 11A.

[0016] Figure 4 1 is a diagram showing an example of the configuration of the linear regulator 42A.

[0017] Figure 5 4 is a diagram showing an example of the configuration of the detection circuit 43A.

[0018] Figure 6 1 is a diagram showing an example of the configuration of the control circuit 46 .

[0019] Figure 7 This is a schematic block diagram showing an example of the configuration of the lighting circuit 11B.

[0020] Figure 8 1 is a diagram showing an example of the configuration of the linear regulator 72A.

[0021] Figure 9 1 is a diagram showing an example of the voltage detection circuit 76 .

[0022] Figure 10 This is a timing chart for explaining the operation of the lighting circuit 11 .

[0023] Figure 11 It is an explanatory diagram showing the lighting state of the light source 20 and the light source 30 .

[0024] Figure 12 1 is an explanatory diagram of the current flowing through the resistor R41 and the resistor R50.

[0025] Figure 13 11B is a schematic block diagram showing an example of the configuration of a lighting circuit 11C as a second embodiment of the lighting circuit 11B.

[0026] Figure 14 This is a timing chart for explaining the operation of the lighting circuit 11 according to the second embodiment.

[0027] Description of Reference Numerals

[0028] 1: Vehicle; 3: Moving part; 4: Fixed part; 10: Lighting unit; 10A: Turn signal lamp; 11, 11A, 11B, 11C: Lighting circuit; 12A, 12B: Cable; 13: Moving unit; 14: Fixed unit; 20: Light source; 21-26: Light emitting unit; 30: Light source; 41A, 41B, 41C: PMOSFET; 42A, 42B, 42C: Linear regulator; 43A, 43B, 43C: Detection circuit; 44, 45: I / F circuit; 46: Control circuit; 47: Capacitor; 48: Schottky barrier diode; 49: NMOSFET; 51: Constant current circuit; 52: Disconnection detection circuit; 53: Voltage adjustment circuit; 54: Comparator; 55, 61: PNP transistor; 56, 60, 67: Capacitor; 57, 62: NPN transistor transistor; 63, 64, 65, 66: resistors; 71A, 71B: PMOSFET; 72A, 72B: linear regulator; 73, 77: NMOSFET; 74, 75: I / F circuit; 76: voltage detection circuit; 81: Zener diode; 82, 83: resistors; 91: constant current circuit; 92: disconnection detection circuit; 93: voltage adjustment circuit; 94: comparator; 100: ECU; 110: battery; 120: switch; 461: timer circuit; 462: latch circuit; L1: power line; L2: ground line; A, B, C1~C4, D, E: terminals; D1~D30: light-emitting elements; R1~R15, R41, R42, R43, R50, R51, R52: resistors; Vbat: power supply voltage; VT: steering voltage; S1~S4: signal. DETAILED DESCRIPTION

[0029] At least the following matters are clarified from the description of this specification and the drawings.

[0030] ======First Embodiment======

[0031] <<Configuration of Turn Signal Lamp 10A>>

[0032] Figure 1 1 is a diagram showing an example of a lighting unit 10 mounted on a vehicle 1. Figure 2 10A is a schematic block diagram showing an example of the system configuration of the turn signal lamp 10A.

[0033] exist Figure 1 The vehicle 1 shown has a fixed portion 4, which is part of the vehicle body, and a movable portion 3 (in this embodiment, a tailgate) that can be opened and closed relative to the fixed portion 4, disposed at the rear of the vehicle body. It should be noted that, while the tailgate is used as an example of movable portion 3, the invention is not limited thereto. For example, in the case of a hatchback vehicle, the hatchback corresponds to the movable portion 3.

[0034] The lighting unit 10 is a vehicle lamp installed at the rear of the vehicle 1, and is composed of a movable unit 13 (tail light (TL) unit) installed at the movable part 3 and a fixed unit 14 (rear combination lamp (RCL) unit) installed at the fixed part 4. Figure 1 As shown, the lighting unit 10 is configured symmetrically with respect to the center in the width direction (left-right direction) of the vehicle 1. In the following description, the right side (the enlarged portion) will be mainly described, but the left side has the same configuration.

[0035] The lighting unit 10 includes a turn signal lamp 10A. The turn signal lamp 10A is Figure 1 The vehicle turn signal lamp, shown by diagonal lines in the enlarged view of FIG, is configured to span the fixed portion 4 and movable portion 3 of vehicle 1. It should be noted that the lighting unit 10 includes, in addition to the turn signal lamp 10A, taillights, brake lights, etc. Furthermore, a wire breakage detection device (not shown) is provided on vehicle 1. This device detects whether the light-emitting element of the turn signal lamp 10A is broken based on the current input from a battery 110 (described later) to the turn signal lamp 10A.

[0036] like Figure 2 As shown, the turn signal lamp 10A includes a lighting circuit 11 , a light source 20 , a light source 30 , and resistors R1 to R15 .

[0037] The light source 20 is a light source including a light emitting element and is provided in the movable part 3. In this embodiment, the light source 20 corresponds to the second light source. The light source 20 is divided into six light emitting parts (light emitting part 21 to light emitting part 26). Figure 1 As shown, the six light emitting portions are arranged in parallel in a substantially horizontal direction (the width direction of the vehicle 1 ).

[0038] Light emitting sections 21 to 26 are connected in parallel, and each light emitting section has light emitting elements connected in series arranged in parallel. For example, in light emitting section 21, light emitting elements D1 and D2 connected in series are connected in parallel with light emitting elements D3 and D4 connected in series.

[0039] In addition, each of the light emitting sections 22 to 26 is provided with four light emitting elements, similar to the light emitting section 21. Therefore, the light source 20 is provided with 24 light emitting elements (D1 to D24).

[0040] It should be noted that the configuration of light-emitting sections 21 through 26 is not limited to the configuration described above; each section may include at least one light-emitting element. For example, multiple light-emitting elements do not need to be connected in series. Furthermore, a single light-emitting section may have three or more columns of light-emitting elements connected in parallel. Furthermore, the number of light-emitting elements, the connection method, and other aspects may differ between light-emitting sections.

[0041] The light source 30 is a light source that is turned on after the light source 20 is turned on, and the light source 30 is provided in the fixed portion 4. In this embodiment, the light source 30 is equivalent to the first light source. The light source 30 is configured with six light-emitting elements (D25 to D30) in series and in parallel. Specifically, the light-emitting element D25 and the light-emitting element D26 connected in series, the light-emitting element D27 and the light-emitting element D28 connected in series, and the light-emitting element D29 and the light-emitting element D30 connected in series are connected in parallel. In addition, the light source 30 is provided in parallel with the light source 20 of the movable portion 3. It should be noted that the configuration of the light source 30 is not limited to the above configuration, as long as it includes at least one light-emitting element.

[0042] The lighting circuit 11 is applied to the turn signal lamp 10A and lights the light emitting elements of the light sources 20 and 30 by supplying a driving current to the light sources 20 and 30. The lighting circuit 11 of this embodiment includes a lighting circuit 11A, a lighting circuit 11B, and cables 12A and 12B.

[0043] Lighting circuit 11A is a circuit that illuminates the light-emitting elements of light source 20 and is provided in movable portion 3. Lighting circuit 11B is a circuit that illuminates the light-emitting elements of light source 30 and is provided in fixed portion 4. The configurations of lighting circuits 11A and 11B will be described later.

[0044] Cable 12A transmits a signal (signal S1, described later) from movable portion 3 to fixed portion 4. Cable 12B transmits a signal (signal S2, described later) from fixed portion 4 to movable portion 3. Note that because movable portion 3 can be opened and closed relative to fixed portion 4, cables 12A and 12B are routed along the axis of movable portion 3. Therefore, cables 12A and 12B are relatively long, for example, 5 to 10 meters in length.

[0045] Resistors R1 to R15 are resistors used to disperse the power consumption of the ICs (specifically, the linear regulators described later) within each lighting circuit. Resistors R1 to R12 are provided in the movable portion 3, and are connected in series between the two light-emitting elements connected in series of the light source 20 and the lighting circuit 11A, respectively. In addition, resistors R13 to R15 are provided in the fixed portion 4, and are connected in series between the two light-emitting elements connected in series of the light source 30 and the lighting circuit 11B, respectively. It should be noted that in this embodiment, a current control resistor (not shown) is also provided in the IC of the lighting circuit 11. By setting the resistance value of the current control resistor, the current value (in other words, the brightness) can be changed for each light-emitting portion (or column of light-emitting elements).

[0046] In addition, Figure 2 In the embodiment, the ECU (electronic control unit) 100 is a control circuit based on a microcomputer or the like, which is installed on the vehicle body. The lighting circuit 11 (lighting circuit 11A and lighting circuit 11B) of this embodiment gradually illuminates the light sources 20 and 30 that constitute the turn signal lamp according to instructions from the ECU 100.

[0047] In addition, Figure 2 In the figure, the switch 120 is a component for applying power to the power line L1 of the turn signal lamp 10A for operating the lighting circuit 11. The switch 120 is, for example, a mechanical contact relay, a contactless relay using a semiconductor element, or the like. The power supply voltage Vbat of the vehicle battery 110 is applied to one end of the switch 120, and the other end of the switch 120 is connected to the power line L1. Therefore, if the switch 120 is turned on based on the instruction of the ECU 100, the power supply voltage Vbat is applied to the power line L1. It should be noted that the power line L1 is a wiring for supplying power to the internal circuits of the lighting circuit 11 (lighting circuit 11A and lighting circuit 11B).

[0048] For example, when the driver of the vehicle 1 operates the direction indicator (not shown) to illuminate the turn signal lamp 10A of the lighting unit 10, the ECU 100 turns the switch 120 on and off at a predetermined cycle Tx.

[0049] Furthermore, ground line L2 is a wiring for applying a ground-level voltage to the internal circuits of lighting circuit 11 (lighting circuit 11A and lighting circuit 11B). Power line L1 and ground line L2 branch off and connect to lighting circuit 11A and lighting circuit 11B, respectively. It should be noted that, although ground line L2 is omitted from the following description, this means that the grounded portion of lighting circuit 11A and lighting circuit 11B is connected to ground line L2. Furthermore, the voltage applied to power line L1 from switch 120 is referred to as steering voltage VT. Therefore, steering voltage VT varies between 0V and power supply voltage Vbat.

[0050] <<Configuration of Lighting Circuit 11A>>

[0051] Figure 3 11A is a schematic block diagram showing an example of the structure of the lighting circuit 11A. Figure 3 The portion of the movable unit 13 shown excluding the light source 20 (light emitting units 21 to 26) and the resistors R1 to R12 corresponds to the lighting circuit 11A. Components constituting the lighting circuit 11A are mounted on a substrate (not shown).

[0052] The lighting circuit 11A includes a diode 40, a PMOSFET 41A, a PMOSFET 41B, a PMOSFET 41C, a linear regulator 42A, a linear regulator 42B, a linear regulator 42C, a detection circuit 43A, a detection circuit 43B, a detection circuit 43C, an interface circuit (hereinafter referred to as an I / F circuit) 44, an interface circuit 45, a control circuit 46, a capacitor 47, a Schottky barrier diode 48, an NMOSFET 49, a resistor R41, a resistor R42, and a resistor R43.

[0053] The diode 40 is a device for protecting the circuit from damage when the battery 110 is connected with the wrong polarity (reverse connection). A steering voltage VT is applied to the anode of the diode 40, and the cathode of the diode 40 is connected to the PMOSFET 41A.

[0054] PMOSFET41A, PMOSFET41B, and PMOSFET41C are elements for supplying power to the power line L1 to the light source 20, and are arranged to be connected in series between the power line L1 (more specifically, the cathode of the diode 40) and the light source 20. The voltage between the PMOSFET41A and the cathode of the diode 40 (node N1) is a value obtained by reducing the voltage drop of the forward voltage of the diode 40 relative to the power supply voltage Vbat, and is set to Vp1 here. The PMOSFET41A, PMOSFET41B, and PMOSFET41C control the conduction / non-conduction (on-off control) through the linear regulator 42A, the linear regulator 42B, and the linear regulator 42C, respectively. In addition, when the power supply voltage Vbat becomes higher than a predetermined value (for example, 11V), the PMOSFET41A is adjusted so that the on-resistance becomes larger (described later). In this embodiment, the PMOSFET41A is equivalent to the second transistor.

[0055] The capacitor 47 and the Schottky barrier diode 48 are circuits for surge protection, and are connected in parallel between the PMOSFET 41C and the light source 20 .

[0056] The linear regulators 42A, 42B, and 42C are circuits for generating drive current based on power from the power supply line L1 and supplying the drive current to the light emitting elements of the light emitting sections of the light source 20 , and are each constituted by an integrated circuit (IC).

[0057] Linear regulator 42A is connected to light-emitting sections 21 and 22 of light source 20 and supplies drive current to light-emitting elements D1 through D8. Linear regulator 42B is connected to light-emitting sections 23 and 24 of light source 20 and supplies drive current to light-emitting elements D9 through D16. Linear regulator 42C is connected to light-emitting sections 25 and 26 of light source 20 and supplies drive current to light-emitting elements D17 through D24. It should be noted that the circuit for supplying drive current to light source 20 is not limited to a linear regulator; other circuits (e.g., a switching regulator) may also be used.

[0058] In this embodiment, linear regulators 42A, 42B, and 42C correspond to the second drive circuit. Furthermore, the drive current supplied by linear regulators 42A, 42B, and 42C to the light-emitting elements of light source 20 corresponds to the second drive current. In this embodiment, three regulators are used to sequentially illuminate the light-emitting components of light source 20. However, this is not limiting. Alternatively, a single regulator (drive circuit) can be used to sequentially illuminate all light-emitting components of light source 20. An example configuration of linear regulators 42A, 42B, and 42C will be described later.

[0059] Detection circuit 43A detects whether all light-emitting elements connected to linear regulator 42A are lit. Detection circuit 43B detects whether all light-emitting elements connected to linear regulator 42B are lit. Detection circuit 43C detects whether all light-emitting elements connected to linear regulator 42C are lit.

[0060] Based on the detection results of each of the above detection circuits, the operation of the next linear regulator (in the case of detection circuit 43C, linear regulators 72A and 72B on the fixed unit 14 side, described later) begins. Note that the configuration examples of detection circuits 43A, 43B, and 43C will be described later.

[0061] The I / F circuit 44 transmits a signal S1 based on the detection result of the detection circuit 43C to the I / F circuit 74 of the fixed unit 14 via the cable 12A. It should be noted that the I / F circuit 44 includes an inverter (not shown) that inverts the logic level of the detection result of the detection circuit 43C and outputs the signal S1. In this embodiment, since the output of the detection circuit 43C is at a low level (hereinafter referred to as an "L" level), the signal S1 becomes a high level (hereinafter referred to as an "H" level).

[0062] In addition, the I / F circuit 44 applies the signal S1 to the gate of the NMOSFET 49 and also sends the signal S1 to the control circuit 46 .

[0063] The I / F circuit 45 receives the signal S2 from the I / F circuit 75 on the fixed unit 14 side and transmits it to the control circuit 46. It should be noted that the signal S2 indicates whether the voltage applied to the light source 30 is higher than a predetermined value (whether preparations for lighting the light-emitting element of the light source 30 are complete).

[0064] The control circuit 46 is a circuit that controls the operation of the linear regulator 42A. For example, when the power is turned on, if the I / F circuit 45 receives a signal S2 indicating that preparations for illuminating the light-emitting elements of the light source 30 are complete (the voltage applied to the light source 30 is higher than a predetermined value), the linear regulator 42A generates a drive current. Furthermore, if the control circuit 46 does not receive the aforementioned signal S2 from the fixed unit 14 within a predetermined period after the I / F circuit 44 sends a signal S1 indicating that all the light-emitting elements of the light source 20 have been illuminated, the linear regulator 42A remains in a stopped state. By stopping the operation of the linear regulator 42A, the PMOSFET 41A turns off, and the light source 20 on the movable unit 13 side is also turned off. An example of the configuration of the control circuit 46 will be described later.

[0065] The resistor R41 is a resistor for adjusting the current value supplied from the battery 110 to the lighting circuit 11A (in other words, adjusting power consumption), and is connected in parallel with the light source 20 (each light emitting unit).

[0066] NMOSFET 49 is connected in series with resistor R41, and signal S1 is applied to the gate. Therefore, NMOSFET 49 is turned on and off based on signal S1. When NMOSFET 49 is on, current flows through resistor R41. Note that resistor R41 acts as a second resistor.

[0067] Resistors R42 and R43 divide the voltage Vp2 at node N2 between PMOSFET 41C and light source 20, and are connected in series between node N2 and ground (ground line L2). A voltage Vdiv at the connection point between resistors R42 and R43 is applied to a comparator 54 (described later) within linear regulator 42A via terminal E of linear regulator 42A.

[0068] <Linear Regulator 42A>

[0069] As described above, the lighting circuit 11A is provided with three linear regulators 42A, 42B, and 42C. Hereinafter, the linear regulator 42A will be mainly described as an example, but the linear regulators 42B and 42C also have the same configuration.

[0070] Figure 4 1 is a diagram showing an example of a linear regulator 42A.

[0071] The linear regulator 42A includes a constant current circuit 51, a disconnection detection circuit 52, a voltage adjustment circuit 53, a comparator 54, and multiple terminals (terminal A, terminal B, terminals C1 to C4, terminal D, and terminal E). Furthermore, the linear regulator 42A is activated by supplying power (applied voltage Vp1) from a node N1 between the diode 40 of the power supply line L1 and the PMOSFET 41A to terminals (not shown). Therefore, the linear regulator 42A can operate when the steering voltage VT reaches the power supply voltage Vbat, regardless of whether the PMOSFETs 41A to 41C are on or off.

[0072] Terminal A is an enable terminal. When a signal of “L” level is applied to terminal A, the linear regulator 42A starts supplying a drive current.

[0073] Terminal B is a terminal for connecting the voltage adjustment circuit 53 to the gate of the PMOSFET 41A. The voltage adjustment circuit 53 adjusts the gate voltage of the PMOSFET 41A via the terminal B.

[0074] Terminals C1 through C4 connect the constant current circuit 51 to the light-emitting elements of the light-emitting sections 21 and 22, and are used to allow a drive current to flow through each light-emitting element. It should be noted that in the linear regulator 42A of this embodiment, four terminals, C1 through C4, are provided as terminals for connecting the light-emitting elements. However, this is not limiting, and the number of terminals may be three or fewer, or five or more.

[0075] Terminal D outputs a signal indicating that the ramping operation in a linear regulator (here, linear regulator 42A) has completed. In this embodiment, detection circuit 43A, described later, detects that a drive current is flowing through light-emitting elements D7 and D8 connected to terminal C4 and forcibly sets terminal D to an "L" level. Consequently, terminal A of the next linear regulator (here, linear regulator 42B) is set to an "L" level, and the supply of drive current begins.

[0076] The terminal E is a terminal for introducing a divided voltage (voltage Vdiv) generated by the resistors R42 and R43 connected in series to the node N2 of the power supply line L1 into the linear regulator 42A.

[0077] The constant current circuit 51 is a circuit that generates a predetermined driving current based on the power of the power line L1. When generating the driving current, the higher the power supply voltage Vbat, the greater the power consumption (the greater the heat generation). The generated driving current is supplied to the light-emitting portion 21 and the light-emitting element of the light-emitting portion 22 via terminals C1 to C4. It should be noted that in this embodiment, the linear regulator 42A, the linear regulator 42B, and the linear regulator 42C have the same structure, but the size of the driving current generated is different, for example, depending on the setting of the size of the internal resistor (not shown). Specifically, the driving current generated by the linear regulator 42A is 40mA, the driving current generated by the linear regulator 42B is 60mA, and the driving current generated by the linear regulator 42C is 80mA.

[0078] Furthermore, a timer (not shown) is provided in the constant current circuit 51, which can stagger the timing of the driving current flowing through the terminals C1 to C4. In this embodiment, after the driving current flows through the terminals C1 and C2 (in other words, the light-emitting elements of the light-emitting section 21) at the same time, the driving current flows through the terminals C3 and C4 (in other words, the light-emitting elements of the light-emitting section 22) at a slightly delayed timing (see Figure 10 ). However, the present invention is not limited thereto, and for example, the timing may be staggered for each terminal.

[0079] The disconnection detection circuit 52 is connected to the connection lines between terminals C1 to C4 and the constant current circuit 51 to detect disconnection. The method for detecting disconnection is not particularly limited, and examples include methods for detecting a voltage increase and methods for detecting a current stop.

[0080] The voltage regulator circuit 53 controls the gate voltage of the PMOSFET (here, PMOSFET 41A). When the linear regulator 42A is activated, the voltage regulator circuit 53 adjusts the gate voltage of PMOSFET 41A via terminal B, turning PMOSFET 41A on. Similarly, the voltage regulator circuit 53 of the linear regulator 42B turns on PMOSFET 41B, and the voltage regulator circuit 53 of the linear regulator 42C turns on PMOSFET 41C. By turning on all of PMOSFET 41A, PMOSFET 41B, and PMOSFET 41C, each light-emitting unit (light-emitting unit 21 to light-emitting unit 26) of the light source 20 is ready for lighting.

[0081] It should be noted that when illuminating a light-emitting element in light-emitting sections 21 and 22, if that light-emitting element is not illuminating (when detected by disconnection detection circuit 52), linear regulator 42A turns off PMOSFET 41A via voltage adjustment circuit 53. Similarly, when illuminating a light-emitting element in light-emitting sections 23 and 24, if that light-emitting element is not illuminating, linear regulator 42B turns off PMOSFET 41B. Furthermore, when illuminating a light-emitting element in light-emitting sections 25 and 26, if that light-emitting element is not illuminating, linear regulator 42C turns off PMOSFET 41C.

[0082] Since the PMOSFETs 41A to 41C are connected in series, when any one of them is turned off, current no longer flows through the light source 20 (all the light sources 20 are turned off).

[0083] The voltage regulating circuit 53 regulates the gate voltage of the PMOSFET 41A based on the output of the comparator 54 (described later). The voltage regulating circuit 53 of the linear regulator 42A corresponds to a second regulating circuit.

[0084] The voltage at terminal E (the voltage Vdiv obtained by dividing voltage Vp2 by resistors R42 and R43) is applied to the inverting input terminal (-terminal) of comparator 54, while the voltage Vref is applied to the non-inverting input terminal (+terminal). Comparator 54 then compares voltage Vdiv with voltage Vref. In this embodiment, the level of voltage Vref and the resistance values of resistors R42 and R43 are determined so that when the steering voltage VT (power supply voltage Vbat) exceeds a predetermined voltage (e.g., 11V), voltage Vdiv becomes greater than voltage Vref. This predetermined voltage (e.g., 11V) corresponds to the third predetermined value.

[0085] Comparator 54 outputs an "L" level signal when voltage Vdiv is higher than voltage Vref, and outputs an "H" level signal when voltage Vdiv is lower than voltage Vref. When the output of comparator 54 is "L", voltage regulator circuit 53 adjusts the gate voltage to increase the on-resistance of PMOSFET 41A. This increases heat generation in PMOSFET 41A, distributing power consumption to PMOSFET 41A.

[0086] In this embodiment, resistors (resistors R1 to R15) are provided between each linear regulator and the light-emitting element of each light-emitting portion. Furthermore, a resistor R41 is provided in parallel with the light source 20, thereby further distributing power consumption. Therefore, when the power supply voltage Vbat is high (specifically, 11V or higher), heating of the linear regulator can be suppressed.

[0087] <Detection Circuit 43A>

[0088] Figure 5 FIG. 4 is a diagram showing an example of the configuration of the detection circuit 43A. Figure 5 In FIG, for the sake of convenience, the position of terminal D is shown offset next to terminal C4.

[0089] The detection circuit 43A detects whether current flows through the light-emitting element (here, the light-emitting element D7 and the light-emitting element D8 connected in series) to which the driving current is supplied last among the plurality of light-emitting elements D1 to D8 connected to the linear regulator 42A. Specifically, the detection circuit 43A detects whether all the light-emitting elements D1 to D8 of the light-emitting units 21 and 22 have been turned on based on the voltage Vp2 of the line LA on the anode side (the anode side of the light-emitting element D7) and the voltage Vp3 of the line LB on the cathode side (the cathode side of the light-emitting element D8) of the light-emitting elements D7 and D8 connected in series. Figure 5 As shown, the detection circuit 43A includes a PNP transistor 55 , a capacitor 56 , an NPN transistor 57 , and resistors R44 and R45 .

[0090] The emitter of the PNP transistor 55 is connected to the line LA and is connected to the base of the PNP transistor 55 via the capacitor 56. The base of the PNP transistor 55 is connected to the line LB via the resistor R44. The collector of the PNP transistor 55 is connected to the base of the NPN transistor 57 via the resistor R45.

[0091] The collector of the NPN transistor 57 is connected to a connection line between the terminal D of the linear regulator 42A and the terminal A of the linear regulator 42B. A voltage Vp2 is applied to this connection line. The emitter of the NPN transistor 57 is grounded.

[0092] With the above configuration, when no drive current flows through light-emitting elements D7 and D8, PNP transistor 55 is turned off, thereby also turning off NPN transistor 57. Consequently, voltage Vp2 is applied to terminal D of linear regulator 42A and terminal A of linear regulator 42B, causing them to go high.

[0093] When the drive current flows through light-emitting elements D7 and D8, PNP transistor 55 turns on. This causes current to be supplied to the base of NPN transistor 57, turning it on. Consequently, terminal D of linear regulator 42A and terminal A of linear regulator 42B are forced to the "L" level, and linear regulator 42B begins supplying the drive current.

[0094] In this way, detection circuit 43A detects that the row of light-emitting elements connected to linear regulator 42A that was last to light up (here, light-emitting element D7 and light-emitting element D8) has been turned on, and starts the operation of linear regulator 42B. This improves the continuity of lighting of multiple light-emitting units when multiple linear regulators are used to light up multiple light-emitting units.

[0095] Detection circuits 43B and 43C have the same configuration as detection circuit 43A, and therefore their description is omitted. It should be noted that detection circuit 43B detects whether all light-emitting elements D9 through D16 of light-emitting units 23 and 24 are lit based on voltage Vp2 on the anode side (anode side of light-emitting element D15) and voltage Vp4 on the cathode side (cathode side of light-emitting element D6) of the light-emitting element (here, light-emitting elements D15 and D16 connected in series) that is last supplied with a drive current among the plurality of light-emitting elements D9 through D16 connected to linear regulator 42B.

[0096] In addition, the detection circuit 43C detects whether all the light-emitting elements D17 to D24 of the light-emitting section 25 and the light-emitting section 26 are turned on based on the voltage Vp2 of the line on the anode side (anode side of the light-emitting element D23) and the voltage Vp5 of the line on the cathode side (cathode side of the light-emitting element D24) of the light-emitting element to which the driving current is last supplied (here, the light-emitting element D23 and the light-emitting element D24 connected in series) among the multiple light-emitting elements D17 to the light-emitting element D24 connected to the linear regulator 42C.

[0097] <Control Circuit 46>

[0098] Figure 6 1 is a diagram showing an example of the configuration of the control circuit 46 .

[0099] The control circuit 46 is configured to include a timer circuit 461 and a latch circuit 462 .

[0100] Signal S1 is input to timer circuit 461 from I / F circuit 44, and signal S2 is input to timer circuit 461 from I / F circuit 45. Timer circuit 461 does not operate when power is on, but starts counting (becoming an operating state) when signal S1 becomes "H" level (terminal D of linear regulator 42C becomes "L" level).

[0101] Then, when signal S2 reaches an "L" level within a predetermined period from the start of counting, timer circuit 461 sets signal S3 to node N5 of latch circuit 462 to an "L" level, thereby activating latch circuit 462. It should be noted that signal S2 at an "L" level indicates that preparations for lighting the light-emitting elements of light source 30 have not yet been completed (the voltage applied to light source 30 is lower than a predetermined value), which will be described in detail later.

[0102] On the other hand, if the signal S2 does not change to the “L” level within a predetermined period after the timer circuit 461 starts counting, the timer circuit 461 stops operating (is reset).

[0103] Latch circuit 462 includes capacitor 60, capacitor 67, PNP transistor 61, NPN transistor 62, and resistors 63, 64, 65, and 66. Resistors 63 and 64, and resistors 65 and 66 are connected in series.

[0104] A voltage Vp1 is applied to one electrode of capacitor 60, and the other electrode of capacitor 60 is connected to the base of PNP transistor 61. As described above, voltage Vp1 is lower than power supply voltage Vbat by the forward voltage of diode 40. Resistor 63 is provided in parallel with capacitor 60.

[0105] The base of the PNP transistor 61 is connected to the collector of the NPN transistor 62 via the resistor 64 , the emitter of the PNP transistor 61 is connected to one electrode of the capacitor 60 , and the collector of the PNP transistor 61 is connected to the base of the NPN transistor 62 via the resistor R65 .

[0106] The emitter of the NPN transistor 62 is grounded, and a signal S3 is input from the timer circuit 461 to a connection node N5 between the collector of the NPN transistor 62 and the resistor 64 .

[0107] One electrode of the capacitor 67 is connected to the base of the NPN transistor 62 , and the other electrode of the capacitor 67 is grounded.

[0108] Furthermore, a connection node N6 between the collector of the PNP transistor 61 and the resistor 65 is connected to the terminal A of the linear regulator 42A. Then, a signal S4 is output from the node N6 to the linear regulator 42A.

[0109] Next, the operation of the control circuit 46 will be described.

[0110] When the power is on, that is, when the steering voltage VT is at the power supply voltage Vbat, the timer circuit 461 and the latch circuit 462 do not operate, and the PNP transistor 61 and the NPN transistor 62 are turned off regardless of the voltage Vp1. Therefore, when the power is on, the signal S4 output from the node N6 is at an "L" level, and the linear regulator 42A starts operating.

[0111] When all the light-emitting units (light-emitting elements) of light source 20 are illuminated, signal S1 becomes "H" level, and timer circuit 461 starts operating. Thereafter, if signal S2 does not become "L" level within a predetermined period, timer circuit 461 stops operating (is reset). On the other hand, if signal S2 becomes "L" level within a predetermined period (when light source 30 is not illuminated), the output signal of timer circuit 461 becomes "L" level.

[0112] When the signal S3 (node N5) from the timer circuit 461 becomes "L" level, the PNP transistor 61 of the latch circuit 462 becomes on. As a result, current flows from the collector of the PNP transistor 61 to the base of the NPN transistor 62 via the resistor 65, and the NPN transistor 62 also becomes on. The collector of the NPN transistor 62 is connected to the base of the PNP transistor 61, thereby maintaining the on state of the PNP transistor 61. That is, the signal S4 from the node N6 is maintained at "H" level, and the operation of the linear regulator 42A stops. As a result, the PMOSFET 41A is turned off, and all the light-emitting parts of the light source 20 are extinguished. It should be noted that when the direction indicator (not shown) for flashing the turn signal lamp 10A is operated, the latch circuit 462 maintains the signal S4 at the above-mentioned logic level.

[0113] <<Configuration of Lighting Circuit 11B>>

[0114] Figure 7 11B is a schematic block diagram showing an example of the structure of the lighting circuit 11B. Figure 7 The portion of the fixed unit 14 shown excluding the light source 30 (light emitting elements D25 to D30) and the resistors R13 to R15 corresponds to the lighting circuit 11B. Components constituting the lighting circuit 11B are mounted on a substrate (not shown).

[0115] The lighting circuit 11B includes a diode 70 , PMOSFET 71A, PMOSFET 71B, a linear regulator 72A, a linear regulator 72B, an NMOSFET 73 , an I / F circuit 74 , an I / F circuit 75 , a voltage detection circuit 76 , and resistors R50 , R51 , and R52 .

[0116] Diode 70, like diode 40 in lighting circuit 11A, is a device used to protect the circuit from malfunctions in the event of incorrect polarity connection of battery 110 (reverse connection). A steering voltage VT (0V to power supply voltage Vbat) is applied to the anode of diode 70, and the cathode is connected to PMOSFET 71A.

[0117] PMOSFET71A and PMOSFET71B are elements that function as switches when supplying power to the power line L1 to the light source 30, and are connected in series between the diode 70 and the light source 30. The voltage between the PMOSFET71A and the diode 70 (node N7) is formed into a value (here, voltage Vp6) that is a voltage drop amount less than the forward voltage of the diode 70 relative to the power supply voltage Vbat. PMOSFET71A and PMOSFET71B control conduction / non-conduction (on-off control) through linear regulators 72A and 72B, respectively. In addition, when the power supply voltage Vbat becomes higher than a predetermined value (for example, 11V), the PMOSFET71A is adjusted by the linear regulator 72A so that the on-resistance becomes larger. It should be noted that the PMOSFET71A is equivalent to the second switch and the first transistor.

[0118] The linear regulator 72A and the linear regulator 72B are circuits for generating a drive current based on the power from the power supply line L1 and supplying the drive current to each light emitting element of the light source 30 , and are formed of an integrated circuit (IC).

[0119] Figure 8 72A. The linear regulator 72A includes a constant current circuit 91, a disconnection detection circuit 92, a voltage adjustment circuit 93, and a comparator 94. It should be noted that the constant current circuit 91, the disconnection detection circuit 92, the voltage adjustment circuit 93, and the comparator 94 are respectively connected to the linear regulator 42A ( Figure 4 )'s constant current circuit 51, disconnection detection circuit 52, voltage adjustment circuit 53, and comparator 54 are the same, so their description is omitted.

[0120] Linear regulator 72A supplies a drive current of 105 mA to light-emitting elements D29 and D30 connected in series with terminal C1, while linear regulator 72B supplies a drive current of 105 mA to light-emitting elements D25 and D26 connected in series with terminal C1, and to light-emitting elements D27 and D28 connected in series with terminal C2. It should be noted that linear regulators 72A and 72B correspond to the first drive circuit. Furthermore, the drive currents supplied by linear regulators 72A and 72B to the light-emitting elements of light source 30 correspond to the first drive current. Furthermore, voltage regulation circuit 93 within linear regulator 72A corresponds to the second control circuit and the first regulation circuit. In this embodiment, two regulators are used to illuminate light source 30 (light-emitting elements D25 to D30), but this is not limiting. For example, a single regulator may be used to illuminate light source 30.

[0121] The I / F circuit 74 receives signal S1 via cable 12A. It should be noted that the I / F circuit 74 includes an inverter (not shown) that inverts the logic value of signal S1 and outputs a signal to terminals A of linear regulators 72A and 72B. For example, when signal S1 is at an "H" level, an "L" level signal is output. This causes linear regulators 72A and 72B to begin supplying drive current at the same time.

[0122] The I / F circuit 75 detects whether the voltage applied to the light source 30 (the voltage Vp7 at the node N8) is higher than a predetermined voltage and transmits a signal S2 indicating this state. The signal S2 is received by the I / F circuit 45 of the movable unit 13 via the cable 12B. Here, if there is a disconnection in the light source 30, the PMOSFET 71A and PMOSFET 71B are controlled to be disconnected by the linear regulator 72A and linear regulator 72B. Moreover, by disconnecting the PMOSFET 71A and PMOSFET 71B, the voltage Vp7 is reduced to 0V. Therefore, in this case, the I / F circuit 75 transmits the signal S2 indicating that the PMOSFET 71A and PMOSFET 71B are disconnected.

[0123] Resistor R50 and NMOSFET 73 are connected in series between power line L1 (here, node N8) and ground (ground line L2). NMOSFET 73 functions as a switch that allows current to flow through resistor R50, and its on / off control is controlled by voltage detection circuit 76. In addition, resistor R50 is a current adjustment resistor used to prevent the vehicle from erroneously detecting that the light-emitting element is disconnected when the power supply voltage Vbat is low. It should be noted that resistor R50 is equivalent to the first resistor, and NMOSFET 73 is equivalent to the first switch.

[0124] The voltage detection circuit 76 is a circuit that controls the on and off of the NMOSFET 73 based on the voltage Vp6 of the node N7 (the cathode side of the diode 70). It should be noted that the voltage detection circuit 76 is equivalent to the first control circuit. Since the voltage detection circuit 76 is connected to the cathode side of the diode 70, it is not affected even when the battery 110 is connected in reverse. In the present embodiment, when the power supply voltage Vbat is lower than 9.6V, the voltage detection circuit 76 turns on (turns on) the NMOSFET 73 based on the voltage Vp6 at this time, and when the power supply voltage Vbat is higher than 9.6V, the voltage detection circuit 76 turns on (turns off) the NMOSFET 73 based on the voltage Vp6 at this time. It should be noted that an example of the configuration of the voltage detection circuit 76 will be described later. In addition, when the power supply voltage Vbat is 9.6V, the voltage Vp6 is, for example, 8.9V (9.6-0.7V (forward voltage)).

[0125] Resistors R51 and R52 are connected in series between node N8, to which the source of PMOSFET 71B and resistor R50 are connected, and ground (ground line L2). Furthermore, the connection point between resistors R51 and R52 is connected to terminal E of linear regulator 72A. Thus, similar to linear regulator 42A on the movable unit 13 side, when steering voltage VT (power supply voltage Vbat) exceeds a predetermined voltage (e.g., 11V), voltage adjustment circuit 93 of linear regulator 72A adjusts the gate voltage to increase the on-resistance of PMOSFET 71A. Note that this predetermined voltage (e.g., 11V) corresponds to the second predetermined value.

[0126] As a result, heat generation in PMOSFET 71A increases, allowing power consumption to be distributed across linear regulator 72A, linear regulator 72B, and PMOSFET 71A. Furthermore, as described above, in this embodiment, the movable portion 3 side also includes a PMOSFET 41A disposed between power line L1 and light source 20, a resistor R41 disposed between PMOSFET 41A and ground (ground line L2), and a linear regulator 42A that increases the on-resistance of the PMOSFET when the power supply voltage Vbat exceeds a predetermined value. This allows power consumption to be distributed across PMOSFET 41A and resistor R41 on the light source 20 (movable portion 3) side. Consequently, power consumption can be further distributed.

[0127] <Voltage Detection Circuit 76>

[0128] Figure 9 2 is a diagram showing an example of the configuration of the voltage detection circuit 76 . Figure 9The voltage detection circuit 76 includes a Zener diode 81 , a resistor 82 , a resistor 83 , a resistor 86 , and an NPN transistor 85 .

[0129] The Zener diode 81 and the resistors 82 and 83 are connected in series between the node N7 of the power line L1 and the ground (ground line L2). The Zener diode 81 adjusts the relationship between the voltage between the resistors R82 and R83 connected in series and the threshold voltage of the NPN transistor 85. The resistors R82 and R83 divide the voltage Vp6 after the voltage is reduced by the Zener diode 81. It should be noted that the Zener voltage of the Zener diode 81 and the resistance values of the resistors R82 and R83 are determined so that when the power supply voltage Vbat is higher than a predetermined value (9.6V in this embodiment), the NPN transistor 85 is turned on, and when the power supply voltage Vbat is lower than the predetermined value, the NPN transistor 85 is turned off. The predetermined value (for example, 9.6V) is equivalent to the first predetermined value.

[0130] The base of the NPN transistor 85 is connected between the resistors R82 and R83 connected in series. The emitter of the NPN transistor 85 is grounded, the voltage Vp6 is applied to the collector via the resistor R86, and the collector is connected to the gate of the NMOSFET 73.

[0131] With the above configuration, when the power supply voltage Vbat is higher than the predetermined value (9.6 V), the NPN transistor 85 is turned on and the NMOSFET 73 is turned off. Therefore, no current flows through the resistor R50.

[0132] On the other hand, when the power supply voltage Vbat falls below a predetermined value (9.6V), NPN transistor 85 turns off. This turns on NMOSFET 73, causing current to flow through resistor R50. As a result, even when the power supply voltage Vbat falls below a predetermined value (9.6V), the power consumption of lighting circuit 11B can be increased. This prevents erroneous detection of a light-emitting element disconnection on the vehicle side.

[0133] It should be noted that the configuration of the voltage detection circuit 76 is not limited to Figure 9 The configuration shown may be any configuration as long as it has the same function. For example, a comparator may be used to turn the NMOSFET 73 on and off according to the power supply voltage Vbat.

[0134] <<Operation of Lighting Circuit 11>>

[0135] Figure 10 It is a timing chart for explaining the operation of the lighting circuit 11. Figure 11 : is an explanatory diagram showing the lighting state of the light source 20 and the light source 30. Figure 12is an explanatory diagram of the current flowing through the resistor R41 and the resistor R50. Figure 11 In the figure, the luminous state (brightness) of the luminous portion is represented by oblique lines. The more oblique lines there are (the narrower the intervals between the oblique lines), the brighter it is.

[0136] For example, when the direction indicator (not shown) for flashing the turn signal lamp is operated, the ECU 100 of the present embodiment repeatedly turns the switch 120 on and off at a predetermined period Tx (for example, 700ms). It should be noted that the periods during which the switch 120 is turned on and off in the period Tx are respectively half the period of the period Tx (350ms). Thus, during the period of half the period Tx, the steering voltage VT is applied to the power supply line L1. In addition, during the period during which the steering voltage VT becomes H level (the period during which the power supply voltage Vbat becomes H level), the light-emitting parts of the light source 20 are sequentially lit ( Figure 10 During the period t0 to t7 (times t0 to t7), the input current is low, so there is a risk that the disconnection detection circuit (not shown) provided on the vehicle side will mistakenly detect that the light sources 20 and 30 are disconnected. Therefore, during this period, the disconnection detection circuit on the vehicle side is shielded to prevent detection.

[0137] First, at time t0, the steering voltage VT becomes "H" level, and the power supply voltage Vbat of the battery 110 is applied to the power supply line L1. As a result, the linear regulators of the lighting circuit 11A and the lighting circuit 11B are activated, forming a state in which the driving current can be supplied to the light source 20 and the light source 30. Then, Figure 3 The linear regulator 42A (specifically, the voltage adjustment circuit 53) turns on the PMOSFET 41A. Similarly, the linear regulator 42B turns on the PMOSFET 41B, and the linear regulator 42C turns on the PMOSFET 41C. As a result, the power supply line L1 and the light source 20 are in a conductive state.

[0138] exist Figure 7Similarly, in the lighting circuit 11B, the linear regulator 72A turns on the PMOSFET 71A, and the linear regulator 72B turns on the PMOSFET 71B. As a result, the power line L1 and the light source 30 are in a conductive state. In addition, the I / F circuit 75 sends an "H" level signal S2 indicating that the voltage applied to the light source 30 is higher than the predetermined voltage (the lighting preparation is completed). The signal S2 is received by the I / F circuit 45 of the movable unit 13 via the cable 12B and input to the control circuit 46. Based on the "H" level signal S2 indicating that the voltage applied to the light source 30 is higher than the predetermined voltage (the lighting preparation is completed), the control circuit 46 outputs an "L" level signal S4 to the A terminal of the linear regulator 42A. The linear regulator 42A starts the operation of supplying the driving current by inputting the "L" level signal S4 to the A terminal.

[0139] First, at time t1, linear regulator 42A supplies a drive current of 40 mA (80 mA in total) to each of the two columns of light-emitting elements (light-emitting elements D1, D2, D3, and D4) in light-emitting unit 21 via terminals C1 and C2. This turns on light-emitting unit 21.

[0140] Next, at time t2, linear regulator 42A supplies a drive current of 40 mA (80 mA total) to each of the two columns of light-emitting elements (light-emitting elements D5, D6, D7, and D8) in light-emitting section 22 via terminals C3 and C4. This causes light-emitting section 22 to illuminate. It should be noted that if the disconnection detection circuit 52 detects that any of the light-emitting elements in light-emitting section 21 or 22 is not illuminated, linear regulator 42A (specifically, voltage regulation circuit 53) turns off PMOSFET 41A. This turns off the light-emitting elements in light source 20.

[0141] Furthermore, detection circuit 43A detects that all the light-emitting elements in light-emitting section 21 and light-emitting section 22 have been turned on based on voltages Vp2 and Vp3 of the light-emitting elements that were last turned on in light-emitting section 21 and light-emitting section 22 (here, light-emitting element D7 and light-emitting element D8), and sets terminal A of linear regulator 42B to the "L" level. As a result, linear regulator 42B begins supplying drive current.

[0142] At time t3, linear regulator 42B supplies a drive current of 60 mA (a total of 120 mA) to each of the two columns of light-emitting elements (light-emitting elements D9, D10, D11, and D12) in light-emitting section 23 via terminals C1 and C2. As a result, light-emitting section 23 illuminates brighter than light-emitting sections 21 and 22.

[0143] Next, at time t4, linear regulator 42B supplies a drive current of 60 mA (a total of 120 mA) to each of the two columns of light-emitting elements (light-emitting elements D13, D14, D15, and D16) in light-emitting section 24 via terminals C3 and C4. Consequently, light-emitting section 24 illuminates at the same brightness as light-emitting section 23. It should be noted that if any of the light-emitting elements in light-emitting section 23 or 24 is not illuminated, linear regulator 42B turns off PMOSFET 41B. This turns off the light-emitting elements in light source 20.

[0144] Furthermore, detection circuit 43B detects that all the light-emitting elements in light-emitting sections 23 and 24 have been turned on based on voltages Vp2 and Vp4 at both ends of the lines connecting light-emitting elements D15 and D16, which were the last to be turned on, respectively. It then sets terminal A of linear regulator 42C to an "L" level. This causes linear regulator 42C to begin supplying drive current.

[0145] At time t5, linear regulator 42C supplies a drive current of 80 mA (a total of 160 mA) to each of the two rows of light-emitting elements (light-emitting elements D17, D18, D19, and D20) in light-emitting section 25 via terminals C1 and C2. As a result, light-emitting section 25 illuminates brighter than light-emitting sections 23 and 24.

[0146] Next, at time t6, linear regulator 42C supplies a drive current of 80 mA (a total of 160 mA) to each of the two columns of light-emitting elements (light-emitting element D21, light-emitting element D22, light-emitting element D23, and light-emitting element D24) in light-emitting section 26 via terminals C3 and C4. As a result, light-emitting section 26 illuminates at the same brightness as light-emitting section 25. It should be noted that if any of the light-emitting elements in light-emitting section 25 or light-emitting section 26 is not illuminated, linear regulator 42C turns off PMOSFET 41C. This turns off the light-emitting elements of light source 20.

[0147] Furthermore, detection circuit 43C detects that all the light-emitting elements in light-emitting sections 25 and 26 (in other words, all the light-emitting elements in light-emitting sections 20) have been turned on based on voltages Vp2 and Vp5 at both ends of the lines connecting light-emitting elements D23 and D24, which were the last to be turned on in light-emitting sections 25 and 26 (in other words, in light source 20). Detection circuit 43C then transmits a signal indicating the detection result (here, a signal at an "L" level) to I / F circuit 44.

[0148] At time t7, the I / F circuit 44 inverts the logic level of the "L" level signal and transmits a "H" level signal S1. This signal S1 is transmitted from the movable portion 3 to the fixed portion 4 via the cable 12A and is received by the I / F circuit 74 of the lighting circuit 11B.

[0149] At time t7, an "H" level signal S1 is applied to the gate of NMOSFET 49, turning on NMOSFET 49 and causing current to flow through resistor R41. Signal S1 is then input to control circuit 46, causing timer circuit 461 of control circuit 46 to start counting.

[0150] The I / F circuit 74 receives the signal S1 at the "H" level, causing the linear regulator 72A and the linear regulator 72B to start supplying a drive current to the light source 30. The linear regulator 72B supplies a drive current of 105 mA to each of the two columns of light-emitting elements (light-emitting element D25, light-emitting element D26 and light-emitting element D27, light-emitting element D28) of the light source 30. In addition, the linear regulator 72A supplies a drive current of 105 mA to the light-emitting element D29 and light-emitting element D30 connected in series. Therefore, a total drive current of 315 mA is supplied to the light source 30, and the light source 30 is illuminated brighter than the light-emitting parts of the light source 20. It should be noted that in this embodiment, the brightness of the light-emitting parts of the light source 20 and the light source 30 is changed, but this is not limited to this. For example, they can also be illuminated with the same brightness. In this embodiment, the light-emitting parts of the light source 20 are connected in parallel with the light source 30, so the brightness can be easily changed.

[0151] Then, when the steering voltage VT becomes the "L" level at time t8, the light sources 20 and 30 are turned off.

[0152] It should be noted that if any of the light-emitting elements D25 to D28 of the light source 30 is not illuminated due to a wire break, etc., the linear regulator 72B turns off the PMOSFET 71B. Similarly, if the light-emitting elements D29 and D30 of the light source 30 are not illuminated, the linear regulator 72A turns off the PMOSFET 71A. As a result, all the light sources 30 are extinguished. Furthermore, a signal S2 of, for example, an "L" level, indicating that the voltage supplied to the light source 30 is lower than a predetermined value, is transmitted from the I / F circuit 75 to the control circuit 46 via the cable 12B and the I / F circuit 45 of the movable portion 3.

[0153] If control circuit 46 receives signal S2 at an "L" level within a predetermined period after receiving signal S1 at an "H" level, it maintains signal S4 to linear regulator 42A at an "H" level. This causes linear regulator 42A to stop supplying drive current, turning off PMOSFET 41A. Consequently, light source 20 is also turned off. Therefore, in this embodiment, if light source 30 is not ready to light, such as when the light-emitting element of light source 30 is disconnected, both light sources 20 and 30 are turned off.

[0154] Thus, in the lighting circuit 11 of this embodiment, the detection result ("H" level signal S1) indicating that all the light-emitting elements of the light source 20 on the movable portion 3 side have been illuminated is transmitted to the fixed portion 4 via the cable 12A, and the supply of driving current to the light source 30 begins. This prevents overlapping or delayed lighting timing even when the light sources 20 and 30 are connected in parallel. Therefore, the continuity of lighting can be improved. Furthermore, in the movable portion 3, based on the detection result of the detection circuit indicating that all the light-emitting elements connected to each linear regulator have been illuminated, the supply of driving current to the next linear regulator is started. Therefore, the continuity of lighting can be improved.

[0155] In addition, the lighting circuit 11 of this embodiment is supplied with power (power supply voltage Vbat) from the battery 110. However, the power supply voltage Vbat is not always constant, but decreases depending on usage. Therefore, there is a risk of adverse conditions occurring depending on the magnitude of the power supply voltage Vbat. For example, when the power supply voltage Vbat is low (e.g., below 9.6V), the input current to the lighting circuit 11 decreases, thereby creating a risk that the vehicle-side disconnection detection circuit (not shown) may mistakenly detect a disconnection in the lighting circuit 11.

[0156] Therefore, in this embodiment, a resistor R50 and an NMOSFET73 are connected in series between the power line L1 of the power supply voltage Vbat applied to the lighting circuit 11B and the ground (ground line L2), and a voltage detection circuit 76 is provided to turn the NMOSFET73 on and off according to the size of the power supply voltage Vbat.

[0157] As described above, the voltage detection circuit 76 turns on the NMOSFET 73 when the power supply voltage Vbat is lower than 9.6V, and turns off the NMOSFET 73 when the power supply voltage Vbat is higher than 9.6V. Figure 10 as well as Figure 12 As shown in FIG. 1 , when the power supply voltage Vbat is lower than 9.6V, current flows through the resistor R50, and the power consumption increases. Figure 10As shown, during the period when the vehicle-side disconnection detection circuit is not disabled (the period between times t7 and t8 when light source 30 is illuminated), NMOSFET 49 is turned on by signal S1, causing current to flow through resistor R41, thereby preventing false detection. It should be noted that when light source 30 is not illuminated due to a disconnection, PMOSFET 71A is turned off, preventing current from flowing through resistor R50. This reduces power consumption.

[0158] On the other hand, when the power supply voltage Vbat is high (for example, above 11V), the power consumption (heat generation) of each linear regulator in the lighting circuit 11 when generating the drive current increases, potentially causing a malfunction. In this embodiment, in the lighting circuit 11B, when the power supply voltage Vbat is above 11V, the linear regulator 72A adjusts the gate voltage to increase the on-resistance of the PMOSFET 71A. This distributes the power consumption to the PMOSFET 71.

[0159] It should be noted that in the lighting circuit 11A, when the power supply voltage Vbat is higher than 11V, the linear regulator 42A adjusts the gate voltage so that the on-resistance of the PMOSFET 41A becomes larger. This allows the power consumption to be distributed to the PMOSFET 41A. Figure 10 as well as Figure 12 As shown in FIG. 1 , current also flows through the resistor R41 connected in parallel with the light source 20, so that the power can also be dispersed to the resistor R41. Figure 12 As shown, when the power supply voltage Vbat becomes higher than 11 V, the on-resistance of the PMOSFET 41A becomes larger, and thus the change in the current flowing through the resistor R41 (the slope with respect to the voltage) becomes smaller.

[0160] =======Second Embodiment======

[0161] Figure 13 1 is a schematic block diagram showing an example of the configuration of a lighting circuit 11C as a second embodiment of the lighting circuit 11B. It should be noted that the configuration of the lighting circuit 11A is the same as that of the first embodiment. Figure 13 In the embodiment, the lighting circuit 11B ( Figure 7 ) Parts with the same structure are marked with the same figure marks and the description is omitted.

[0162] The lighting circuit 11C of the second embodiment is different from the lighting circuit 11B of the first embodiment in that it includes a resistor R53 and an NMOSFET 77 .

[0163] The resistor R53 is a resistor for adjusting the value of the current supplied from the battery 110 to the lighting circuit 11C, and is connected in parallel with the light source 30 .

[0164] NMOSFET 77 is connected in series with resistor R53, and a signal S1 is applied to its gate from I / F circuit 74. Therefore, NMOSFET 77 is turned on and off based on signal S1. In this embodiment, when I / F circuit 74 receives signal S1 at an "H" level, NMOSFET 77 is turned on, causing current to flow through resistor R53.

[0165] Figure 14 This is a timing chart illustrating the operation of the lighting circuit 11 according to the second embodiment. Since signal S1 is applied to the gate of NMOSFET 77, NMOSFET 77 switches on and off at the same timing as NMOSFET 49 in the movable portion 3. In other words, current flows through resistor R53 at the same timing as resistor R41 in the movable portion 3.

[0166] Specifically, from time t1 to t7, when the light-emitting elements of light source 20 are sequentially illuminated, signal S1 is at an "L" level, and thus NMOSFET 77 is turned off, preventing current from flowing through resistor R53. At time t7, signal S1 becomes "H" level, turning NMOSFET 77 on, allowing current to flow through resistor R53. Furthermore, at time t8, signal S1 becomes "L" level, turning NMOSFET 77 off, preventing current from flowing through resistor R53.

[0167] Thus, in the second embodiment, a resistor R53 connected in parallel with the light source 30 is provided in the lighting circuit 11C on the side of the fixed portion 4. During the period when the light source 30 is lit, a current flows through the resistor R53. Thus, the fixed portion 4 can also adjust the input current in a manner that increases the input current, which can further suppress the vehicle side's disconnection detection circuit (not shown) from erroneously detecting a disconnection. In addition, when the power supply voltage Vbat is higher than 11V, the linear regulator 72A is adjusted so that the on-resistance of the PMOSFET 71A becomes larger. Therefore, the current characteristic of the resistor R53 with respect to the input voltage is the same as that of the PMOSFET 71A. Figure 12 By providing the resistor R53 in the fixed portion 4 in this manner, when the power supply voltage Vbat is high, the power consumption can be further dispersed.

[0168] =====Summary======

[0169] The lighting circuit 11 of this embodiment has been described above. The lighting circuit 11 includes linear regulators 72A and 72B that supply drive current to the light source 30 including light-emitting elements D25 to D30. Furthermore, a resistor R50 and an NMOSFET 73 are connected in series between a power line L1 to which a power supply voltage Vbat is applied and a ground (ground line L2). The voltage detection circuit 76 turns on the NMOSFET 73 when the power supply voltage Vbat is lower than 9.6V and turns off the NMOSFET 73 when the power supply voltage Vbat is higher than 9.6V. This increases the current flow when the power supply voltage Vbat is low, thereby improving power consumption.

[0170] Furthermore, a PMOSFET 71A is provided between the power supply line L1 and the light source 30, and a resistor R50 and an NMOSFET 73 are provided between the PMOSFET 71A and the ground (ground line L2). When no current flows when the light-emitting elements D29 and D30 of the light source 30 are illuminated, the linear regulator 72A turns off the PMOSFET 71A. This prevents current from flowing through the resistor R50 when the light source 30 is not illuminated, thereby reducing power consumption.

[0171] Furthermore, voltage detection circuit 76 controls the on / off switching of NMOSFET 73 based on the cathode voltage of diode 70, which has power supply voltage Vbat applied to its anode and is connected to PMOSFET 71A. This prevents the circuit from being affected when battery 110 is connected in reverse.

[0172] Furthermore, when the power supply voltage Vbat is higher than 11 V, the voltage adjustment circuit (not shown) in the linear regulator 72A adjusts the gate voltage of the PMOSFET 71A to increase the on-resistance of the PMOSFET 71A. Thus, when the power supply voltage Vbat is high, the power consumption of the PMOSFET 71A can be increased, thereby distributing the power consumption.

[0173] The lighting circuit 11 also includes a linear regulator 42A that supplies a drive current to the light source 20, which includes light-emitting elements D1 through D24; a PMOSFET 41A disposed between the power supply line L1 and the light source 20; and a resistor R41 disposed between the PMOSFET 41A and ground (ground line L2). When the power supply voltage Vbat exceeds 11V, the voltage adjustment circuit 53 of the linear regulator 42A adjusts the PMOSFET 41A to increase its on-resistance. This allows power consumption to be distributed across the PMOSFET 41A and the resistor R41.

[0174] Furthermore, the light source 30, resistor R50, NMOSFET 73, and linear regulator 72A are provided in one of the fixed portion 4 of the vehicle 1 and the movable portion 3 that can be opened and closed relative to the fixed portion 4 (in this embodiment, the fixed portion 4), while the light source 20, PMOSFET 41A, resistor R41, and linear regulator 42A are provided in the other of the fixed portion 4 and the movable portion 3 (in this embodiment, the movable portion 3). Thus, when the power supply voltage Vbat is higher than 11V, power consumption can be distributed between the fixed portion 4 and the movable portion 3.

[0175] The above embodiments are provided to facilitate understanding of the present invention and are not intended to limit the present invention. In addition, the present invention can be modified and improved without departing from the spirit thereof, and the present invention naturally includes equivalents thereof.

Claims

1. A lighting circuit, which is a lighting circuit applied to a direction indicator light for a vehicle, wherein: The lighting circuit comprises: a first driving circuit that supplies a first driving current to a first light source comprising at least one light-emitting element; A first resistor and a first switch are provided between a power line to which a power voltage is applied and a ground line and are connected in series; as well as a first control circuit, wherein when the power supply voltage is lower than a first predetermined value, the first control circuit turns on the first switch, and when the power supply voltage is higher than the first predetermined value, the first control circuit turns off the first switch; The first resistor is connected in parallel with the first light source.

2. The lighting circuit according to claim 1, wherein: The lighting circuit comprises: a second switch, disposed between the power line and the first light source; as well as The second control circuit turns off the second switch when a predetermined light emitting element of the first light source is turned on and a current does not flow through the predetermined light emitting element. The first resistor and the first switch are arranged between the second switch and the ground line.

3. The lighting circuit according to claim 2, wherein: The lighting circuit includes a diode, the power supply voltage is applied to the anode of the diode, and the cathode of the diode is connected to the second switch. The first control circuit controls on and off of the first switch based on the voltage of the cathode.

4. The lighting circuit according to claim 2 or 3, wherein: The second switch is a first transistor, The lighting circuit includes a first adjustment circuit configured to increase an on-resistance of the first transistor when the power supply voltage is higher than a second predetermined value.

5. The lighting circuit according to any one of claims 1 to 3, wherein: The lighting circuit comprises: a second driving circuit that supplies a second driving current to a second light source comprising at least one light-emitting element; a second transistor, disposed between the power line and the second light source; a second resistor, disposed between the second transistor and the ground line; as well as The second adjustment circuit increases the on-resistance of the second transistor when the power supply voltage is higher than a third predetermined value.

6. The lighting circuit according to claim 5, wherein: The first light source, the first resistor, the first switch, and the first control circuit are provided in one of a fixed portion of the vehicle and a movable portion that can be opened and closed relative to the fixed portion. The second light source, the second transistor, the second resistor, the second driving circuit, and the second adjustment circuit are provided on the other of the fixed portion and the movable portion.

7. A lighting circuit, which is a lighting circuit used for a direction indicator light for a vehicle, wherein: The lighting circuit comprises: a driving circuit that supplies a driving current to a light source including at least one light-emitting element; a transistor provided between a power line to which a power voltage is applied and the light source; a resistor disposed between the transistor and a ground line; as well as an adjustment circuit, wherein when the power supply voltage is higher than a predetermined value, the adjustment circuit increases the on-resistance of the transistor; The transistor is connected in series with the light source, The resistor is connected in parallel with the light source.

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